Panjange nigrifrons group, 1983

Bernhard A. Huber & Charles Leh Moi Ung, 2016, The Panjange nigrifrons group in Borneo (Araneae: Pholcidae): high diversity in Sarawak, apparent absence in Sabah, European Journal of Taxonomy 184 (184), pp. 1-32 : 3-6

Panjange nigrifrons group

Diagnosis

Within Panjange , males of the nigrifrons group are easily distinguished from other species groups ( lanthana and cavicola groups) by presence of distal cheliceral apophyses (arrow in Fig. 18 ) and by ventral apophysis on palpal femur (arrow in Fig. 30 ); also by absence of long elongation of palpal tarsus (convergently also in some species of lanthana group) and – females – by absent or very short scape (relatively long in Pa. nigrifrons and Pa. kapit sp. nov.). From representatives of the very similar Pholcus minang group by ridges ventrally on procursus ( Figs 17 , 26 , 34 , 49 ; absent in Pa. tahai comb. nov.), by ventral apophysis on palpal femur, and possibly by wide opening of tarsal organ (figs 481 and 686 in Huber 2011). From other similar genera on Borneo ( Pholcus group of genera sensu Huber 2011: Calapnita Simon, 1892 ; Leptopholcus Simon, 1893 ; Pholcus Walckenaer, 1805 ; Uthina Simon, 1893 ) by combination of male coloration (e.g., Figs 8 , 61 ; male ocular area and palps black; similar only in some Pholcus ), by bipartite distal apophyses on male chelicerae ( Figs 35 , 47 ; similar only in some Calapnita ), by cylindrical rather than worm-shaped abdomen ( Figs 8-15 , 61–68 ; in contrast to Calapnita and Leptopholcus ).

Description

Male

MEASUREMENTS. Total body length ~4–5; carapace width 0.9–1.2; leg 1 length ~35–50; tibia 1 length ~9–12; tibia 2/tibia 4 length 1.05–1.15; tibia 1 L/d ~95–115.

COLOR. In life ( Figs 8, 10–11 , 61, 63–66 ) mostly pale ochre-yellow to whitish with distinctively black ocular area and palps; sternum whitish; legs with dark patellae and tibia-metatarsus joints; abdomen with darker brown to black marks dorsally and laterally, sometimes slightly reddish-brown.

BODY. Carapace without median furrow. Ocular area raised, eye triads on stalks of variable length ( Figs 2–7 ), either with or without pointed processes arising from near PME ( Figs 2–7 ). AME always absent, but sometimes with small pigment marks in AME area. Clypeus unmodified. Abdomen cylindrical, slightly angular above spinnerets ( Figs 10 , 64 ). Male gonopore with four epiandrous spigots ( Fig. 27 ); each ALS with large widened spigot, pointed spigot, and six cylindrically-shaped spigots (of varying sizes; Figs 28 , 44 ); PMS with two spigots each.

CHELICERAE. With pair of simple proximal lateral processes and distinctively bipartite pair of distal apophyses ( Figs 18 , 35 , 71 ); without modified hairs; without stridulatory ridges.

PALPS. Coxa unmodified; trochanter with long retrolatero-ventral apophysis (short only in Pa. nigrifrons ); femur usually with distinctive finger-shaped ventral apophysis (e.g., Figs 30 , 70 ), only in Pa. pueh sp. nov. with more conical ventral process ( Fig. 17 ); patella triangular in lateral view; tibia with two trichobothria; palpal tarsus sometimes with small dorsal process (e.g., Fig. 70 ); palpal tarsal organ capsulate with very wide opening (cf. figs 481 and 686 in Huber 2011); procursus relatively complex, only in Pa. tahai comb. nov., with hinge dividing proximal and distal parts; parallel ridges on procursus usually distinct and in high number (e.g., Figs 17 , 30 , 34 , 49 ), in Pa. nigrifrons only three ridges, in Pa. tahai comb. nov. without ridges; procursus sometimes with complex membranous processes ( Figs 21– 23 , 77–79 ), in some species with distinctive process in distal pit ( Figs 22 , 80 ; see also figs 478 and 683 in Huber 2011); bulb with strong proximal sclerite (e.g., Figs 16 , 29 , 33 ), with relatively simple appendix and weakly sclerotized embolus; embolus with subterminal fringes or processes ( Figs 24–25 , 51 , 75 ).

LEGS. Without spines, without curved hairs, few vertical hairs; retrolateral trichobothrium very proximal (tibia 1: at 1.5–3% of tibia length), prolateral trichobothrium absent on tibia 1, present on other tibiae. Tarsus 1 with ~30–40 pseudosegments, very indistinct except distally. Tarsus 4 with single row of ventral comb-hairs of Pholcus - type (cf. Huber & Fleckenstein 2008) ( Fig. 45 ).

Female

Similar to male but without eye stalks; eye triads on low humps and never with pointed processes ( Fig. 38 ); chelicerae unmodified; legs slightly shorter than in male. Epigynum weakly sclerotized, with distinct ‘knob’; either without scape ( Fig. 19 ), with very short scape ( Figs 31 , 72 , 84 ), or with medium to long scape ( Figs 36 , 87 ). Internal genitalia with pair of pore plates of variable shape, sometimes with very complex system of internal folds of unknown function ( Figs 59 , 90, 93 ).

Monophyly and relationships

The cladistic analysis in Huber & Nuñeza (2015) included all available species of Panjange except for Pa. tahai comb. nov. It resolved the Pa. nigrifrons group as monophyletic, but with weak support (only one synapomorphy: the ventral apophysis on the male palpal femur). Internal relationships and relationships to other species groups in Panjange and to Pholcus also remained unconvincing. Preliminary molecular data (including six species of the Pa. nigrifrons group and six species of the Pa. lanthana group; A. Valdez-Mondragón, D. Dimitrov, B.A. Huber, unpubl. data) suggest that Panjange is not monophyletic and that the Pa. nigrifrons group is in fact more closely related to species currently in Pholcus than to the Pa. lanthana group. Morphological data partly point in the same direction (e.g., the bipartite cheliceral apophyses that occur in the Pa. nigrifrons group as well as in the Pholcus minang group) but problems arise from character conflict, dubious homologies of bulbal sclerites, and missing SEM data for many species (especially of the potentially closely related Pholcus minang group).

Pholcus tahai [now Panjange tahai ( Huber, 2011) comb. nov.] from Kalimantan was not included in the cladistic analysis in Huber & Nuñeza (2015). Depending on how the main bulbal process beside the embolus is coded (as unknown, as uncus, or as appendix) the species is either resolved as sister to Panjange or as member of the Pa. nigrifrons group. Each solution has its problems: the procursus of Panjange tahai comb. nov. partly looks very different from that of representatives of the Pa. nigrifrons group: it lacks ventral ridges and it has a hinge dividing proximal and distal parts; on the other hand, the tip of the procursus (compare fig. 684 in Huber 2011 with Fig. 80 herein) and the shape of the tarsal organ (compare figs 481 and 685 in Huber 2011) remind strongly of other representatives of the Pa. nigrifrons group. One further hint toward a closer affinity with the Pa. nigrifrons group is biogeography: Pa. tahai comb. nov. occurs on Borneo like all other species of the Pa. nigrifrons group, while all species of the Pholcus minang group (to which the species was previously assigned) are from Sumatra and the Malay Peninsula ( Huber 2011).

Natural history

All species observed in the field share a very similar microhabitat and web. They were consistently found in webs among low vegetation in well preserved forests, usually at about 0.5 m above the ground or even lower. The domed webs had a diameter of about 15–20 cm and were at their apex connected to the underside of a leaf where the spiders rested. At some localities, large numbers of cecidomyiid flies were found hanging in the webs together with the spiders. Egg-sacs are slightly elongated and contain approximately 20– 30 eggs (e.g., Figs 13 , 62 ).

Composition

As construed here, the Panjange nigrifrons group now includes ten species: Panjange bako Huber, 2011 ; Pa. iban Huber, 2011 ; Pa. kapit sp. nov.; Pa. kubah sp. nov.; Pa. niah sp. nov.; Pa. nigrifrons Deeleman-Reinhold & Deeleman, 1983; Pa. pueh sp. nov.; Pa. sedgwicki Deeleman-Reinhold & Platnick, 1986 ; Pa. seowi sp. nov.; Pa. tahai ( Huber, 2011) comb. nov. Judging from known distribution patterns in Sarawak and from the large poorly sampled forests of Kalimantan, the group is likely to contain several times as many species. However, the absence of Panjange in northeastern Borneo may be real rather than an artifact of poor sampling. Our own collecting at nine localities east of Niah did not produce a single specimen of Panjange ( Fig. 95 ; see Discussion).

Distribution

Known from Borneo only ( Fig. 1 ).

Figures

Fig. 1. Known distribution of the Panjange nigrifrons group.

Fig. 95. Known distributions of the genera Panjange Deeleman-Reinhold & Deeleman, 1983 and Aetana Huber, 2005 in northern Borneo, showing the distinctness of western and eastern regions (distribution of Aetana from Huber et al. 2015).

Figs 16 – 20. Panjange pueh Huber, sp. nov. (ZFMK Ar 14576 – 77). 16 – 17. Left male palp, prolateral and retrolateral views. 18. Male ocular area, clypeus, and chelicerae, oblique frontal view (arrow points at distal cheliceral apophysis). 19 – 20. Cleared female genitalia, ventral and dorsal views. Abbreviations: a = appendix; b = genital bulb; e = embolus; f = femur; p = procursus; ps = proximal bulbal sclerite; tr = trochanter. Scale lines: 0.5 mm.

Figs 29 – 32. Panjange niah Huber, sp. nov. (ZFMK Ar 14579 – 80). 29 – 30. Left male palp, prolateral and retrolateral views (arrow points at ventral femur apophysis). 31 – 32. Cleared female genitalia, ventral and dorsal views. Abbreviations: a = appendix; b = genital bulb; e = embolus; f = femur; p = procursus; ps = proximal bulbal sclerite; tr = trochanter. Scale lines: 0.5 mm.

Figs 21 – 28. Panjange pueh Huber, sp. nov. (ZFMK Ar 14576). 21. Left procursus and bulb, prolateral view. 22. Left procursus, prolateral distal view (arrow points to distinctive process in distal pit). 23. Prolateral membranous process on left procursus. 24 – 25. Tip of embolus, distal views. 26. Left procursus and bulb, prolatero-distal view. 27. Male gonopore. 28. Male ALS. Abbreviations: a = appendix; b = genital bulb; e = embolus; p = procursus. Scale lines: 20 µm (28); 30 µm (25, 27); 40 µm (23); 60 µm (22, 24); 100 µm (26); 200 µm (21).

Figs 33 – 34. Panjange kapit Huber, sp. nov. (ZFMK Ar 14583). Left male palp, prolateral and retrolateral views. Abbreviations: a = appendix; b = genital bulb; e = embolus; f = femur; p = procursus; ps = proximal bulbal sclerite; tr = trochanter. Scale line: 1 mm.

Figs 46 – 51. Panjange kapit Huber, sp. nov. (ZFMK Ar 14583). 46. Male prosoma, frontal view. 47. Right distal male cheliceral apophysis. 48. Right procursus (and bulbal processes), dorsal view. 49. Ridges on left procursus, prolateral view. 50. Tip of left appendix, prolateral view. 51. Tip of left procursus (and embolus), ventral view. Abbreviations: a = appendix; e = embolus; p = procursus. Scale lines: 30 µm (47); 60 µm (50); 100 µm (49, 51); 200 µm (48); 400 µm (46).

Figs 8 – 15. Live specimens. 8 – 9. Panjange pueh Huber, sp. nov., Ƌ and ♀ from Pueh. 10 – 14. Pa. kapit Huber, sp. nov. from Kapit. 10 – 11. Adult Ƌ, 12. Penultimate instar Ƌ, 13 – 14. ♀ with egg-sac. 15. Pa. niah Huber, sp. nov., ♀ with egg-sac from Niah.

Figs 61 – 68. Live specimens. 61 – 62. Pa. iban Huber, 2011, Ƌ and ♀ with egg-sac from Semengoh. 63 – 64. Pa. kubah Huber, sp. nov., Ƌ from Kubah. 65 – 68. Pa. seowi Huber, sp. nov., Ƌ, ♀, and ♀ with egg-sac from Penrissen.

Figs 35 – 37. Panjange kapit Huber, sp. nov. (ZFMK Ar 14583 – 84). 35. Male ocular area, clypeus, and chelicerae, oblique frontal view. 36 – 37. Cleared female genitalia, ventral and dorsal views. Scale lines: 0.5 mm.

Figs 2 – 7. Male prosomata, oblique frontal views. 2. Panjange pueh Huber, sp. nov. (ZFMK Ar 14576). 3. Pa. niah Huber, sp. nov. (ZFMK Ar 14579). 4. Pa. kapit Huber, sp. nov. (ZFMK Ar 14583). 5. Pa. nigrifrons Deeleman-Reinhold & Deeleman, 1983 (RMNH, Sepaku). 6. Pa. kubah Huber, sp. nov. (ZFMK Ar 14587). 7. Pa. seowi Huber, sp. nov. (ZFMK Ar 14590).

Figs 38 – 45. — 38 – 41. Panjange niah Huber, sp. nov. (ZFMK Ar 14580). 38. Female prosoma, frontal view. 39 – 40. Comb-hairs on female tarsus 4. 41. Epigynum, ventral view. — 42 – 45. Panjange kapit Huber, sp. nov. (ZFMK Ar 14583). 42. Tip of left procursus, retrolatero-distal view. 43. Base of palpal trichobothrium. 44. Male ALS. 45. Comb-hairs on male tarsus 4. Scale lines: 10 µm (40, 43 – 44); 20 µm (45); 40 µm (39); 60 µm (42); 200 µm (38, 41).

Figs 69 – 73. Panjange kubah Huber, sp. nov. (ZFMK Ar 14587 – 88). 69 – 70. Left male palp, prolateral and retrolateral views (arrows point at distinctive processes). 71. Male ocular area, clypeus, and chelicerae, oblique frontal view. 72 – 73. Cleared female genitalia, ventral and dorsal views. Scale lines: 0.5 mm.

Figs 74 – 81. Panjange kubah Huber, sp. nov. (ZFMK Ar 14587 – 88). 74. Left bulb, prolateral (slightly distal) view. 75. Tip of left embolus. 76. Epigynum, ventral view. 77 – 78. Left procursus, dorso-distal and prolateral views (arrows point at distinctive membranous process). 79. Membranous process of left procursus. 80. Tip of left procursus, distal view. 81. Female ALS. Abbreviations: a = appendix; b = genital bulb; e = embolus. Scale lines: 10 µm (81); 20 µm (80); 40 µm (79); 80 µm (75); 100 µm (77 – 78); 200 µm (74, 76).

Figs 82 – 85. Panjange seowi Huber, sp. nov. (ZFMK Ar 14590 – 91). 82 – 83. Left procursus, prolateral and retrolateral views (arrows point at distinctive processes). 84 – 85. Cleared female genitalia, ventral and dorsal views. Scale lines: 0.5 mm.

Figs 86 – 94. Female genitalia, untreated in ventral view, cleared in ventral and dorsal views. 86 – 88. Panjange nigrifrons Deeleman-Reinhold & Deeleman, 1983 (RMNH, Sepaku). 89 – 91. Pa. kubah Huber, sp. nov. (ZFMK Ar 14588). 92 – 94. Pa. seowi Huber, sp. nov. (ZFMK Ar 14591).

Figs 52 – 60. Female genitalia, untreated in ventral view, cleared in ventral and dorsal views. 52 – 54. Panjange pueh Huber, sp. nov. (ZFMK Ar 14577). 55 – 57. Pa. niah Huber, sp. nov. (ZFMK Ar 14580). 58 – 60. Pa. kapit Huber, sp. nov. (ZFMK Ar 14584).